When keeping ornamental fish including saltwater fish or freshwater fish in an aquarium, a filtering device is usually installed for the purpose of keeping the water in the aquarium clean.
As a filtering device for an aquarium, an underwater installation type filtering device designed to be installed within an aquarium and an outside installation type filtering device designed to be installed outside an aquarium are well known. Furthermore, the outside installation type filtering device can be classified into an aquarium direct installation type filtering device which is to be directly attached to an upper portion or a wall surface portion of an aquarium and an independent installation type filtering device which is to be installed independently from an aquarium.
Among these filtering devices, an outside installation type aquarium, especially an independent installation type filtering device, can easily be increased in size and can have excellent filtering ability as compared with an underwater installation type filtering device.
Conventionally, as the independent installation type filtering device, filtering devices as disclosed in the following Patent Documents 1 to 3 are well known. Such filtering device includes a casing, a filtering material provided in the casing, an inlet pipe for introducing water from an aquarium into the casing of the filtering device, an outlet pipe for returning the water filtered by the filtering device to the aquarium, and a discharge pump for sending water into the discharge pipe.
Patent Document 1: Utility Model Registration No. 3018619 (FIGS. 1, 2, and 4)
Patent Document 2: Japanese Unexamined Laid-Open Patent Publication No. H9-174079 (FIGS. 3 and 10)
Patent Document 3: Japanese Unexamined Laid-open Patent Publication No. H11-137926 (FIGS. 1 and 3)